TweetFollow Us on Twitter

June 94 - Somewhere in QuickTime

SOMEWHERE IN QUICKTIME

Basic Movie Playback Support

PETER HODDIE


Adding basic QuickTime movie playback support to most applications is simple, often just one day's work. Developers who want to do this turn first to Inside Macintosh: QuickTime , where it says to use a movie controller component. In Inside Macintosh: QuickTime Components,  you find some elementary movie controller code samples, followed by a large reference section. This is usually enough to get started, but there are a few common problems. This column addresses some of them, with special attention to compatibility with future QuickTime releases. It assumes you're familiar with basic QuickTime and movie controller concepts.

OPENMOVIEFILE
All QuickTime movie files contain a movie resource, usually stored in the file's resource fork, and the actual movie data, stored in the file's data fork. To support cross-platform QuickTime movies, QuickTime's Movie Toolbox also allows the movie resource to be stored in the data fork along with the movie's data. (To learn how this is done, see John Wang's Somewhere in QuickTime column in develop  Issue 17.) The usual sequence of calls to load a QuickTime movie from a file is: OpenMovieFile, NewMovieFromFile, CloseMovieFile.

In the common case of the movie resource stored in the resource fork, OpenMovieFile returns a file reference to the resource fork of the movie file, NewMovieFromFile loads the movie resource from that resource fork and creates a QuickTime movie, and CloseMovieFile closes the resource fork.

But if the movie was created on a computer running Microsoft Windows and QuickTime for Windows (using AdobeTM Premiere, for example), the file won't have a resource fork. Still, you can use the exact same sequence of calls. When OpenMovieFile is called, the file reference returned refers to the data fork; NewMovieFromFile loads the movie from the data fork, and CloseMovieFile closes the data fork.

Some developers don't use OpenMovieFile; they use FSpOpenResFile instead. While this works fine with movies made specifically for the Macintosh, it fails miserably otherwise. There's a sample movie with no resource fork, QuickBuck, on this issue's CD, so you can test this situation with your applications.

If you need to know whether OpenMovieFile opened the resource fork or the data fork, you can examine the file reference it returns, as follows:

pascal Boolean IsDataFork(short fileReference)
{
    FCBPBRec    anFCB;
    Str63       fName;

    anFCB.ioVRefNum = 0;
    anFCB.ioRefNum = fileReference;
    anFCB.ioFCBIndx = 0;
    fName[0] = 0;
    anFCB.ioNamePtr = (StringPtr)fName;

    if (PBGetFCBInfoSync(&anFCB) != noErr)
        return false;

    return (anFCB.ioFCBFlags & 0x0200) == 0;
}

NEWMOVIECONTROLLER
When you need a user interface for playing a movie, you should use NewMovieController to create a movie controller appropriate for use with that movie.

A common mistake is to instead use the Component Manager routine FindNextComponent or OpenDefaultComponent to locate a movie controller. This finds the first movie controller in the system's list of registered components. QuickTime has always contained only one movie controller, so this worked fine. However, future versions of QuickTime will almost certainly include other movie controllers, so the first one isn't necessarily the most appropriate one.

To help track down those offending applications that don't use NewMovieController, there's a system extension on this issue's CD which contains a different movie controller. You'll also find a movie, Other Controller Movie, that should  invoke the sample movie controller. If any other movie invokes the sample movie controller, or if Other Controller Movie invokes the standard movie controller, the application you're testing isn't using NewMovieController. This will cause undesirable results in the not-so-distant future.

UPDATE EVENTS
If you use a movie controller in the recommended way (that is, you allow all events to be filtered through MCIsPlayerEvent), it updates all areas of the window covered by the movie and the movie's controls. Usually that's all a window contains, so all update events are completely handled by the movie controller. This works so well that some developers actually forget to support update events at all.

Unfortunately, it's not always so simple. QuickTime movies aren't always rectangular. If the movie is round and the window is rectangular (as in Figure 1), there are areas in the window that are not covered by the movie or the movie controls. Any update events in these areas are the responsibility of the application. [IMAGE 022-025_Somewhere_in_QT_2.GIF]

Figure 1. A nonrectangular movie

For applications using MCIsPlayerEvent, handling update events is easy:

BeginUpdate(theWindow);
EraseRect(&theWindow->portRect);
EndUpdate(theWindow);

This sample code erases all areas of the window besides the movie and its controls. Normally, erasing the portRect of the window would erase the entire window, but MCIsPlayerEvent sets the update region to just the areas it didn't already handle.

If you don't handle update events, things are even worse than you might think. The window won't be updated correctly, but more important, the operating system will keep generating new update events. Update events have a higher priority than idle events, so the system will never generate idle events -- the movie will receive no time to play.

A sample round movie is provided on this issue's CD so that you can test your handling of update events.

KEYSTROKES
The standard movie controller provides for extensive keyboard control from the user but ignores keystrokes by default. They can be enabled with a single line of code:

MCDoAction(mc, mcActionSetKeysEnabled, (void *)true);

You might want to enable keystrokes only under certain circumstances. For example, a word processor might allow the movie controller to receive keystrokes only when a movie is selected. You can use the mcActionSetKeysEnabled action to enable and disable keystrokes as necessary.

MOUSE CLICKS
All applications that use the standard movie controller pass mouse clicks on to the controller. But not all applications pass mouse clicks made on the movie itself. Failure to pass such clicks will cause problems with any future movie controllers that allow the user to interact directly with the contents of the movie. For example, a movie controller might allow the user to pan around the image by dragging on the movie; if mouse clicks aren't passed through, using either MCClick or MCIsPlayerEvent, this feature won't work.

MOVIE CONTROLLER HELP
The standard Apple movie controller is simple enough for most people to understand immediately, but it supports help balloons anyway (future movie controllers might be less obvious). If Balloon Help is turned on, the standard movie controller automatically displays help for its various controls, as well as for the QuickTime movie itself. You don't have to do anything at all for this to work.

A problem can arise if your application puts up its own help balloons. Since QuickTime movies are often embedded in a larger document, the help balloons may conflict. The result is that the movie controller's help balloon alternates with the application's help balloon. (Use Balloon Help with the Scrapbook desk accessory included with QuickTime to see what this looks like.)

The preferred solution is to stop the application from displaying a help balloon when the cursor is over a QuickTime movie or movie control. It's easy to tell whether a given point in a window intersects the movie:

Boolean PointInMovieController(MovieController
        mc, WindowPtr w, Point where)
{
    RgnHandle   rgn;
    Boolean     result = false;

    rgn = MCGetWindowRgn(mc, w);
    if (rgn != nil) {
        result = PtInRgn(where, rgn);
        DisposeRgn(rgn);
    }
    return result;
}

A second solution is to stop the movie controller from displaying its help balloons -- necessary if you want to display your own help for QuickTime movies. To do this, install an action filter on the movie controller. Every action that occurs in the movie controller (play, step, update, key down, and so on) is passed through a single filter function. Through this filter, an application can gain access to all activity that occurs in the movie controller.

The MegaMovies application on this issue's CD provides a window that displays events that pass through the action filter. The action of interest is mcActionShowBalloon. When this action is sent, QuickTime is about to put up a new help balloon. One of the parameters passed to the action filter is a pointer to a Boolean. The filter can set this Boolean to false to tell the movie controller not to show a balloon. The following code fragments show how to install a simple action filter to prevent the movie controller from displaying help balloons.

pascal Boolean noBalloonsActionFilter 
                (MovieController mc, short action, 
                 void *params, long refCon)
{
    if (action == mcActionShowBalloon)
        *(Boolean *)params = false;
    return false;
}

. . .
MCSetActionFilterWithRefCon(mc, 
        &noBalloonsActionFilter, 0);

CURSOR SHAPE
Many applications change the shape of the cursor depending on what it's currently over. The standard movie controller never changes the cursor, but other movie controllers might want to. Unfortunately, many applications need to control the cursor themselves -- when a movie controller changes the cursor, these applications change it back immediately.

A simple solution is for applications to change the cursor only when it's first placed over a movie. (To determine whether a point is over the movie, use PointInMovieController.) After that, let the movie controller control the cursor until it exits the area over the movie. To give the movie controller the opportunity to change the cursor's shape, you must call either MCIsPlayerEvent or MCIdle frequently while the cursor is over the movie, even if the movie is stopped. The sample movie controller on this issue's CD changes the cursor when it's over the movie, providing an easy way to debug such a scheme.

WINDOW ALIGNMENT
A simple way to improve a QuickTime movie's playback performance is to ensure that the movie is at a good location on the screen. The exact definition of a "good location" varies, based on the screen depth and the processor. A typical good location is one where the first pixel of each scan line begins on a long-word boundary. This allows the decompressors to write data in the most efficientway. On slower machines, proper placement can provide the necessary performance improvement to deliver smooth playback.

Fortunately, applications don't have to understand the details of how to find a good location. QuickTime's Image Compression Manager provides routines to position a window at these locations. When you create a window, you can use AlignWindow to move it to a good location before making it visible. If a window is to be moved, AlignScreenRect will modify the chosen location to make it a good location. When the user drags a window, call DragAlignedWindow instead of DragWindow to place the window in a good location. Examples of these calls are shown below.

WindowPtr   w;
Movie       m;
Rect            r;

// Code to create a properly aligned window.
w = GetNewCWindow(128, nil, (WindowPtr)-1);
m = getMovie();
GetMovieBox(m, &r);
AlignWindow(w, false, &r, nil);

// Code to drag a window with a movie in it and
// keep the window aligned properly.
GetMovieBox(m, &r);
DragAlignedWindow(w, theEvent.where, nil, &r, nil);

These alignment routines were added in QuickTime 1.5, so make sure that QuickTime 1.5 or later is installed before you call them.

MOVIE CONTROLLER EDITING
The standard movie controller supports the editing commands Undo, Cut, Copy, Paste, and Clear, but this functionality is turned off by default. To turn it on, call MCEnableEditing as follows:

MCEnableEditing(mc, true);

You can then use movie controller routines to implement editing:

Movie       m = nil;

switch (editMenuSelection) {
    case menuUndo:      MCUndo(mc);
                            break;
    case menuCut:       m = MCCut(mc);
                            break;
    case menuCopy:      m = MCCopy(mc);
                            break;
    case menuPaste: MCPaste(mc, nil);

Now you have to enable and disable the various menu items. You could call MCGetControllerInfo, which returns a long word of flags indicating, among other things, which Edit menu items should be enabled.With QuickTime 1.5, there's an easier way: call MCSetUpEditMenu, and the movie controller will enable and disable the items in the Edit menu for you.

MCSetUpEditMenu(mc, theEvent.modifiers, editMenuHandle);
[IMAGE 022-025_Somewhere_in_QT_3.GIF]

Standard [IMAGE 022-025_Somewhere_in_QT_4.GIF]

Modified


This routine will even change the menu contents if appropriate. For example, Undo becomes Undo Paste if the last movie controller action was Paste; after Undo Paste is chosen, it becomes Redo Paste. What's more, if the user holds down modifier keys when pulling down a menu, other commands change as well. For example, holding down the Option key changes Paste to Add and Clear to Trim. (See Figure 2.)

Figure 2. Standard and modified Edit menus

MCSetUpEditMenu assumes the Edit menu is arranged in the standard way. If yours is nonstandard, you'll need to use MCGetMenuString to obtain the appropriate text for each standard Edit command, and then enable and disable the menu items according to the information from MCGetControllerInfo.

JUST DO IT
It's so easy to add movie playback support that it's often well worth the effort. As long as you keep these few simple things in mind, you shouldn't have any problems, even with future versions of QuickTime.

PETER HODDIE writes code to introduce hard-to-find bugs into QuickTime. In his spare time he writes code to introduce even harder-to-find bugs into QuickTime. *

Thanks to Jim Batson, Ken Doyle, and John Wang for reviewing this column. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Vienna 3.0.6 :5eaf312: - RSS and Atom ne...
Vienna is a freeware and Open-Source RSS/Atom newsreader with article storage and management via a SQLite database, written in Objective-C and Cocoa, for the OS X operating system. It provides... Read more
Kodi 15.1.rc1 - Powerful media center to...
Kodi (was XBMC) is an award-winning free and open-source (GPL) software media player and entertainment hub that can be installed on Linux, OS X, Windows, iOS, and Android, featuring a 10-foot user... Read more
Bookends 12.5.8 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Access the power of Bookends directly from Mellel, Nisus Writer Pro, or MS Word (... Read more
Chromium 44.0.2403.125 - Fast and stable...
Chromium is an open-source browser project that aims to build a safer, faster, and more stable way for all Internet users to experience the web. Version 44.0.2403.125: This release contains a number... Read more
iMazing 1.2.2 - Complete iOS device mana...
iMazing (was DiskAid) is the ultimate iOS device manager with capabilities far beyond what iTunes offers. With iMazing and your iOS device (iPhone, iPad, or iPod), you can: Copy music to and from... Read more
Audio Hijack 3.2.0 - Record and enhance...
Audio Hijack (was Audio Hijack Pro) drastically changes the way you use audio on your computer, giving you the freedom to listen to audio when you want and how you want. Record and enhance any audio... Read more
FontExplorer X Pro 5.0.1 - Font manageme...
FontExplorer X Pro is optimized for professional use; it's the solution that gives you the power you need to manage all your fonts. Now you can more easily manage, activate and organize your... Read more
Calcbot 1.0.2 - Intelligent calculator a...
Calcbot is an intelligent calculator and unit converter for the rest of us. Featuring an easy-to-read history tape, expression view, intuitive conversion, and much more! Features History Tape -... Read more
MTR 5.0.0.1 - The Mac's oldest and...
MTR (was MacTheRipper)--the Mac's oldest and smartest DVD-backup app--is now updated to version 5.001 MTR -- the complete toolbox, not a one-trick, point-and-click extractor. MTR is intended for... Read more
LibreOffice 4.4.5.2 - Free, open-source...
LibreOffice is an office suite (word processor, spreadsheet, presentations, drawing tool) compatible with other major office suites. The Document Foundation is coordinating development and... Read more

Card King: Dragon Wars - Tips, Tricks an...
[Read more] | Read more »
Pac-Man Championship Edition DX has brou...
Bandai Namco has released Pac-Man Championship Edition DX on iOS and Android, which features the classic arcade gameplay that we've all grown to love. Pac-Man Championship Edition DX can be enjoyed in much shorter bursts than the arcade versions... | Read more »
Cosmonautica (Games)
Cosmonautica 1.1 Device: iOS Universal Category: Games Price: $6.99, Version: 1.1 (iTunes) Description: Cast off! Are you ready for some hilarious adventures in outer space? | Read more »
Rescue humanity from a Demon horde in An...
Angel Stone is Fincon's follow up to the massively successful Hello Hero and is out now on iOS and Android. You play as a member of The Resistance, a group of mighty human warriors who have risen up in defiance of the Demon horde threatening to... | Read more »
Gallery Doctor (Photography)
Gallery Doctor 1.0 Device: iOS iPhone Category: Photography Price: $2.99, Version: 1.0 (iTunes) Description: Free up valuable iCloud and iPhone storage with Gallery Doctor, the only iPhone cleaner that automatically identifies the... | Read more »
You Against Me (Games)
You Against Me 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: A simple game… You. Me. Claim, steal, lock, score, win! | Read more »
Yep, it's True - Angry Birds 2 is O...
The not exactly rumors were true and the birds are back. Angry Birds 2 has come to the App Store and the world will... well I suppose it'll still be the same, but now we have more bird-flinging options! [Read more] | Read more »
You Could Design Your Own Card for Chain...
If you've ever wanted to create your own item, weapon, trap, or even monster for Chainsaw Warrior: Lords of the Night, this is your chance. Auroch Digital is currently holding a contest so that fans can fight to the death (not really) to see which... | Read more »
Bitcoin Billionaire is Going Back in Tim...
If you thought you managed to buy everything there is to buy in Bitcoin Billionaire and make all the money, well you though wrong. Those of you who made it far enough might remember investing in time travel - and it looks like that investment is... | Read more »
Domino Drop (Games)
Domino Drop 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: Domino Drop is a delightful new puzzle game with dominos and gravity!Learn how to play it in a minute, master it day by day.Your... | Read more »

Price Scanner via MacPrices.net

27-inch 3.5GHz 5K iMac on sale for $81 off MS...
Adorama has the 27″ 3.5GHz 5K iMac on sale for $2218, $81 off MSRP, including a free copy of Apple’s 3-Year AppleCare Protection Plan. Shipping is free, and Adorama charges sales tax in NY & NJ... Read more
Back-to-School with Tablet and Smartphone Acc...
Belkin helps you prepare for the coming school year with a wide variety of the latest mobile and tablet accessories to outfit both grade school and college students. The line-up includes charging... Read more
11-inch MacBook Airs on sale for $100 off MSR...
Best Buy has 11-inch MacBook Airs on sale for $100 off MSRP. Choose free shipping or free local store pickup (if available). Sale prices for online orders only, in-store prices may vary: - 11″ 1.6GHz... Read more
iPad Air 2 on sale for up to $100 off MSRP
Best Buy has iPad Air 2s on sale for up to $100 off MSRP on their online store for a limited time. Choose free shipping or free local store pickup (if available). Sale prices available for online... Read more
Sale! 13-inch MacBook Pros on sale for $100 o...
B&H Photo has 13″ MacBook Pros on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.5GHz/500GB MacBook Pro: $999.99 save $100 - 13″ 2.7GHz/128GB Retina... Read more
Sale! Save $100 on 13-inch MacBook Airs this...
B&H Photo has the 13″ 1.6GHz/128GB MacBook Air on sale for $899.99 including free shipping plus NY tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model.... Read more
Worldwide Tablet Market Decline Continues, Ap...
The worldwide tablet market declined -7.0% year-over-year in the second quarter of 2015 (2Q15) with shipments totaling 44.7 million units according to preliminary data from the International Data... Read more
TP-LINK TL-PA8030P KIT Powerline Featuring Ho...
Consumer and business networking products provider TP-LINK is now shipping its TL-PA8030P KIT AV1200 3-Port Gigabit Passthrough Powerline Starter Kit that expands your home’s network over its... Read more
Apple refurbished iPad Air 2s available for u...
The Apple Store has Apple Certified Refurbished iPad Air 2s available for up to $140 off the price of new models. Apple’s one-year warranty is included with each model, and shipping is free: - 128GB... Read more
Updated Apple iPad Price Trackers
We’ve updated our iPad Air Price Tracker and our iPad mini Price Tracker with the latest information on prices and availability from Apple and other resellers. Read more

Jobs Board

*Apple* Retail - Multiple Positions (US) - A...
Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, you're also the Read more
Infrastructure Engineer - *Apple* /Mac - Hil...
Infrastructure Engineer - Apple /Mac Job Code: 1608 # of openings: 1 Description Our fortune 500 client is looking to hire an experienced Infrastructure Engineer to join Read more
Executive Administrative Assistant, *Apple*...
…supporting presentation development for senior leadership. * User experience with Apple hardware and software is preferred. Additional Requirements The following list Read more
*Apple* Bus Company is now hirin - Apple Bus...
Apple Bus Company is now hiring school bus drivers in the Pettis County area. Class B CDL preferred. Free training provided. No nights or weekends required. Flexible Read more
*Apple* Certified Mac Technician - Updated 6...
…and friendly, hands-on technical support to customers troubleshooting and repairing Apple /Mac products with courtesy, speed and skill. Use your problem-solving skills Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.